Swap if arms if the condition is inverted

master
Graham 5 years ago
parent 556923559c
commit 27346725e3
  1. 26
      deob-ast/src/main/java/dev/openrs2/deob/ast/transform/IfElseTransformer.java

@ -2,6 +2,8 @@ package dev.openrs2.deob.ast.transform;
import com.github.javaparser.ast.CompilationUnit; import com.github.javaparser.ast.CompilationUnit;
import com.github.javaparser.ast.NodeList; import com.github.javaparser.ast.NodeList;
import com.github.javaparser.ast.expr.Expression;
import com.github.javaparser.ast.expr.UnaryExpr;
import com.github.javaparser.ast.stmt.IfStmt; import com.github.javaparser.ast.stmt.IfStmt;
import com.github.javaparser.ast.stmt.Statement; import com.github.javaparser.ast.stmt.Statement;
import dev.openrs2.deob.ast.visitor.NegateExprVisitor; import dev.openrs2.deob.ast.visitor.NegateExprVisitor;
@ -34,13 +36,35 @@ public final class IfElseTransformer extends Transformer {
throw new IllegalArgumentException(); throw new IllegalArgumentException();
} }
private static boolean isNot(Expression expr) {
return expr.isUnaryExpr() && expr.asUnaryExpr().getOperator() == UnaryExpr.Operator.LOGICAL_COMPLEMENT;
}
@Override @Override
public void transform(CompilationUnit unit) { public void transform(CompilationUnit unit) {
unit.findAll(IfStmt.class).forEach(stmt -> { unit.findAll(IfStmt.class).forEach(stmt -> {
stmt.getElseStmt().ifPresent(elseStmt -> { stmt.getElseStmt().ifPresent(elseStmt -> {
var condition = stmt.getCondition();
var thenStmt = stmt.getThenStmt(); var thenStmt = stmt.getThenStmt();
if (isIf(thenStmt) && !isIf(elseStmt)) { if (isIf(thenStmt) && !isIf(elseStmt)) {
stmt.setCondition(stmt.getCondition().accept(new NegateExprVisitor(), null)); stmt.setCondition(condition.accept(new NegateExprVisitor(), null));
stmt.setThenStmt(elseStmt);
stmt.setElseStmt(thenStmt);
} else if (!isIf(thenStmt) && isIf(elseStmt)) {
/*
* Don't consider any more conditions for swapping the
* if/else branches, as it'll introduce another level of
* indentation.
*/
return;
}
/*
* Prefer if (a) over if (!a). We don't swap != as it makes
* checking bitwise flags look worse.
*/
if (isNot(condition)) {
stmt.setCondition(condition.accept(new NegateExprVisitor(), null));
stmt.setThenStmt(elseStmt); stmt.setThenStmt(elseStmt);
stmt.setElseStmt(thenStmt); stmt.setElseStmt(thenStmt);
} }

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